Previous research has demonstrated a functionally significant interaction between the opiate and catecholamine (CA) neurotransmitter systems, as evidenced by anatomical, physiological, and behavioral data. While there have been numerous investigations of this interaction in the soma-dendritic and in selected terminal regions of the noradrenergic and dopaminergic systems, almost no investigations have explored possible interactions between these systems in limbic structures. For this reason, and since work in this laboratory has implicated the importance of opiate/norepinephrine (NE) interactions within the amygdaloid complex for the regulation of learning and memory processes, this research will focus on the limbic system. These experiments will examine the effects of unilateral 6-hydroxydopamine (6-OHDA) and electrolytic lesions of various dopamine (DA) and NE cell groups upon the quantitative autoradiographic localization of mu and delta receptor binding sites within various limbic structures. The target areas for this investigation will include the septal nuclei, bed nucleus of the stria terminalis, nucleus accumbens, nucleus of the diagonal band, amygdaloid complex, and the hippocampal formation. The major advantages of these techniques for analyzing opiate receptor binding following manipulations of components of the CA systems include sensitivity and spatial resolution. In addition, unilateral disruption of CA input to the forebrain will permit comparisons between the effects of experimental and control treatments within the same animals. The specific issues which will be addressed by the proposed research include: 1) whether the localization of any changes in opiate receptor binding corresponds to the known distribution of CA terminals in the target regions; 2) whether one or both of the examine opiate receptor subpopulations are involved; 3) whether effects on receptor binding are specific to some or all of the terminal fields of the involved CA projection to the limbic system and 4) whether denervation of the NE projections to the limbic system which arise from lateral tegmental NE cells produces any alteration in opiate receptor binding in the targeted areas.